Marble is a kind of metamorphic rocks, generally is in white. It also can be gray, green, yellow, ect., while containing impurities. Marbles are in granoblastic texture or palimpsest texture, with massive structure, and formed by metamorphism of carbonate rock.
Limestone is a kind of sedimentary rocks, the mineral component is mainly the calcite. Generally in gray or white, but the color might be darker if there are many impurities contains. Limestone is in compactness texture, crystalloblastic texture, and bioclastic texture. The nature is crisp, bubbles will occur while having chemical reaction with the diluted hydrochloric acid.